Preheat the Oven: Preheat your oven to 400°F (200°C). Line a baking sheet with aluminum foil for easy cleanup.
Prepare the Fillets: Pat the Chilean sea bass fillets dry with a paper towel. This will help them achieve a nice sear. Season both sides with salt and pepper.
Make the Marinade: In a small mixing bowl, combine olive oil, lemon zest, lemon juice, minced garlic, and chopped parsley. Mix well.
Marinate the Fillets: Place the fillets on the prepared baking sheet. Brush both sides of the fillets with the marinade, ensuring they are well-coated.
Add White Wine (Optional): If using white wine, pour it around the fillets on the baking sheet. This will create a flavorful steam bath for the fish as it cooks.
Bake the Fillets: Place the baking sheet in the preheated oven. Bake for 12-15 minutes or until the fish is opaque and flakes easily with a fork. The internal temperature should reach 145°F (63°C).
Baste with Butter: While the fish is baking, melt the unsalted butter in a small saucepan over low heat. Once the fish is cooked, remove it from the oven and baste the fillets with the melted butter for added richness.
Serve: Transfer the Chilean sea bass fillets to serving plates. Garnish with extra chopped parsley and lemon slices if desired. Serve immediately with your favorite side dishes.